1. Field of the Invention
The present invention relates to a circuit breaker and, more particularly, to a device for preventing withdrawing and inserting in a circuit breaker capable of capable of preventing a breaker body from being inserted into or withdrawn from a cradle while a circuit breaker is being closed by interworking with an opening and closing operation of the circuit breaker, to thereby secure stability of the circuit breaker and prevent damage to the circuit breaker.
2. Description of the Related Art
In general, a vacuum circuit breaker (referred to as a ‘circuit breaker’, hereinafter) is a protection device for automatically breaking power quickly when there is a fault in a power system as well as transmitting and receiving, switching and stopping power by using a vacuum interrupter as an arc extinguishing medium. Namely, the circuit breaker rapidly spreads and extinguishes an arc product, which is generated during an opening and closing in case of a normal load and when an accident current is broken, to quickly separate a circuit to thereby protect the circuit and the device.
The circuit breaker generally includes a cradle, a breaker main body, a carriage, and auxiliary devices. Here, the carriage includes various mechanic devices integrally coupled with the breaker main body and selectively move the breaker main body to the cradle.
In order to operate the circuit breaker, the breaker main body must be electrically connected with the cradle. Namely, the carriage must be completely moved to the cradle and respective contact points of the breaker main body integrally coupled with a front side of the carriage must be completely bound with the cradle to perform a closing operation. However, if the carriage is inserted and withdrawn while the circuit breaker is being closed, a serious safety accident would occur or the device would be damaged, so an apparatus for preventing inserting and withdrawing of carriage is required to prevent the carriage from being inserted or withdrawn while the circuit breaker is being closed.
FIG. 1 is a perspective view showing the configuration of the related art circuit breaker. FIGS. 2 and 3 are perspective views showing the related art device for transferring a breaker main body of a circuit breaker. FIG. 4 is a partial cross-sectional view showing the configuration of the related art device for transferring a circuit breaker.
As shown in FIG. 1, the related art device for transferring breaker main body of the circuit breaker includes a carriage 100 on which a breaker main body 140, which is coupled to or separated from a mounting frame 130 installed at a rear side of a cradle 120, is loaded, an withdrawal handle 200 for moving the carriage 100 forward and backward, a braking unit for limiting a transfer distance of the carriage 100 transferred by the withdrawal handle 200, and a girder assembly 300 for supporting the withdrawal handle 200.
The carriage 100 includes a box body 101 having an open upper side and including a wall body 101a formed with a certain height on an outer circumferential surface, and two wheels 102 installed at both sides of the box body 101 and drawn in or out along guide rails installed at an inner side of both side walls of the cradle 120.
As shown in FIGS. 2 to 4, the withdrawal handle 200 includes a lead screw 201 inserted in a forward/backward direction of a through hole 101b formed on a front wall body 101a of the box body 101, a transfer nut 202 installed at an inner side of the front wall body 101a of the box body 101 in a state of being screw-coupled with the lead screw 201, a channel-shaped bracket 203 fixed to the box body 101 to prevent the transfer nut 202 from being released, and a handle 213 detachably attached to a front end portion in order to rotate the lead screw 201 forward and backward.
The transfer nut 202 includes a female screw portion 202a coupled with an outer circumferential surface of the lead screw 201, a guide recesses 202b each having a different depth, are formed at each of upper and lower surfaces of the transfer nut 202, and a guide recess 202c is formed on an outer circumferential surface of the transfer nut 202.
A girder 209 fixed to a rear end portion of the lead screw 201 may move forwardly and backwardly without a movement on a pair of travel rails 212 and 212′ installed in a lengthwise direction on an inner side of the box body 101 of the carriage 100.
The girder assembly 300 includes a post bar 303 having a space part 301 formed at an inner side thereof and bearing-supporting to transfer a rotational force to a front end portion of the lead screw 201 which has passed through a fixing hole formed at the center, a sliding plate (not shown) installed to be movable in a left and right direction at both inner sides of the post bar 303, left and right handles 305 and 305′ fixed to the left and right sliding plates and installed to be protruded from an outer side of the post bar 303, and a positioning spring (not shown) for moving the left and right sliding plates to an outer side in order to insert an end portion 304a into position recess 120a formed on both wall bodies of the cradle 120.
A braking unit 204 is installed near the transfer nut 202, and when the rotation of the transfer nut 202 is limited, the braking unit 204 fixes a breaking basic body 140 loaded on the carriage 100 interworking with the transfer nut 202 at stopping and operational positions.
As shown in FIG. 4, the braking unit 204 is installed in a diagonal direction of a bracket 203 of the forward and reverse rotation preventing pins 205 and 205′ so as to be inserted into or released from guide recesses 202b formed on the upper and lower surface of the transfer nut 202. The forward and reverse rotation preventing pins 202 and 205′ are connected with connection plates 206 and 206′ by means of left and right driving pins 207 and 207′. The left and right driving pins 207 and 207′ are elastically supported by springs 208 and 208′. The left and right driving pins 207 and 207′ are pressed to the side of the rudder 209 installed at an end portion of the lead screw and the side of the girder assembly 300 when the carriage 100 moves forward and backwards. Guide pins 210 for correctly positioning the transfer nut 202 when the forward rotation preventing pin 204 or the reverse rotation preventing pin 205′ are released from the guide recesses 202b of the transfer nut 202 by the left and right driving pins 207 and 207′ are installed at a pair of support plates 211 and 211′ installed at certain interval in a vertical direction at the bracket 203 so as to be inserted into the guide recess 202c of the transfer nut 202.
Reference numeral 141 denotes an upper booth bar, 214 denotes a bearing, and 500 denotes a transfer device.
In the breaker including the device 500 for transferring the breaker main body of the related art circuit breaker configured as described above, in order to assemble the device, the carriage 100 is put on the cradle 120, the sliding plates are moved in an inward direction by using the left and right handles 305 and 305′ of the girder assembly 300, and the girder assembly 300 is fixed so that the end portions 304a of the sliding plate can be inserted into the position recesses 120a. 
In the state that the girder assembly 300 is fixed on the cradle 120, the carrier 100 is moved backwardly to couple the breaker main body 140 and the mounting frame 130 so as to be used, and during operation, current is led into an interruptor (no reference numeral given) installed at the inner side of the breaker main body 140 through the upper booth bar 141. The led-in current is drawn out through a lower booth bar (not shown), and in this operational state, when an accident occurs, the interruptor instantaneously interrupts current.
In the state that the interruptor interrupts current, the breaker main body 140 is disassembled from the mounting frame 130. To this end, in a state that the breaker main body 140 is coupled with the mounting frame 130, an operator may couple the withdrawal handle 213 to a front end of the lead screw 201 and rotate the lead screw 201 counterclockwise. Then, the bracket 203 and the carriage 100 are moved by the transfer nut 202, and the breaker main body 140 is moved forward to disassemble the breaker main body 140 from the mounting frame 130.
In the state that the breaker main body 140 is disassembled from the mounting frame 130, a repairing operation is performed. Thereafter, when the breaker main body 140 is coupled to the mounting frame 130, the operator rotates the lead screw 201 clockwise by using the withdrawal handle 213. Then, the carriage 100 is moved backward and the breaker main body 140 is coupled to the mounting frame 130.
The rotation of the transfer nut 202 moving in the forward and backward direction at the lead screw 201 is limited by the braking unit 204. When the carriage 100 is not completely moved to the front side, namely, in case of a non-operational state, the right driving pin 207′ is brought into contact with one side of the girder assembly 300, the reverse rotation preventing pin 205′ is released from the guide recess 202b of the transfer nut 202, idly rotating, and thus, the carrier 100 cannot move any longer.
When the carriage 100 is in a state of being completely moved to the rear side, namely, in case of the operational state, the transfer nut 202 is completely moved to the rear side along the lead screw 201, so the left driving pin 207 is brought into contact with the side of the rudder 209 installed at the rear end portion of the lead screw 201, the forward rotation preventing pin 205 is released from the guide recess 202b of the transfer nut 202, making the transfer nut 202, idly rotated, so the transfer nut 202 does not move any longer.
In the related art circuit breaker, even in an unstable state that each the end portion 304a of the sliding plates is respectively not inserted into the position recesses 120a, the withdrawal handle 200 may be inserted into the girder assembly 300 so as to operate, so a problem arises in that an abnormal withdrawing and inserting operation may be performed.